1. Field of the Disclosure
The present disclosure relates generally to devices having memory, and more particularly to device having a multiple port memory.
2. Description of the Related Art
The amount of power consumed by an integrated circuit memory device is generally proportional to the voltage at which the memory device operates. Therefore, it can be beneficial to reduce the operating voltage of a memory device. Unfortunately, circuit functionality and reliability can be impaired when the operating voltage approaches the threshold voltage of the transistors incorporated at the memory device. Functionality and reliability issues are further affected in a negative way by the reduced physical size of transistors and other circuit components resulting from advances in integrated circuit fabrication technology. Memory devices can be particularly susceptible to these issues.
Individual transistors and other components included at a memory device naturally exhibit variations in their electrical characteristics resulting from the manufacturing process. These variations can affect the electrical behavior of the memory. Therefore, a circuit designer considers these variations when designing the memory device so that the manufactured memory device achieves its stated operating specifications, including a minimum operating voltage and a minimum access speed.
A memory can be classified as a dynamic memory or a static memory depending upon whether its bit cells need to be periodically refreshed. Each bit cell is generally configured to store a single binary bit of information. A bit cell can be further classified as a single port bit cell or a multiple port bit cell based on how data is stored and retrieved from the bit cell. For example, a single port bit cell includes one port that is used to both store and retrieve information at the bit cell. A dual port bit cell can include two ports that each support storage and retrieval of information at the bit cell independent and asynchronous from the other port. For example, information can be stored at a dual port bit cell via one port and the information can be retrieved via another port. A dual port bit cell is particularly susceptible to problems associated with low operating voltage, compared to a single port bit cell.